Posts Made By: Tom Lacovik

i've heard a 1.25" diagonal won't bring most eps to focus. true? if so, am i better off with a 2" diagonal even though I only have 1.25" eps (pentax xls) maybe I would add a 2" EP later for wide field use. but for now. am i better off (weight wise or for any other reason) with a 1.25" diagonal and some kind of extender?

i've heard a 1.25" diagonal won't bring most eps to focus. true? if so, am i better off with a 2" diagonal even though I only have 1.25" eps (pentax xls) maybe I would add a 2" EP later for wide field use. but for now. am i better off (weight wise or for any other reason) with a 1.25" diagonal and some kind of extender?

I have a 2" SCT diagonal (sold the SCT, kept the accessories) that doesn't mate to my MK67 Mak because the mak has a drawtube whereas my diagonal has a visual back type screw on thread.

That half of the diagonal comes off, and looks like it could take a threaded barrel which would make it like a 'regular' diagonal after all, and so I could keep it instead of having to by a new one for my Mak. I guess it's a 2" ID but threaded on the outside piece of tube.

Does someone here have such a thing hanging around they could give/sell me? Could one be made easily (not by me, but you know)? If your advice is to have me find a machinist...what should I tell them: dimensions please, and material to use (unlikely I'll find a machinist/astronomer 2-in-one so any specifics will help). One note: the MK67 is notorious for needing a 'little extra' back focus, so, if I CAN specify length, i'd probably add 1/2" over whatever 'regular' length of these things is (what is 'regular length' by the way for these?)

Thanks for any dimensions? freebies? advice? whatever you got...THANKS!

Tom.

Okay here's my dilemma: Buy a Coulter 13.1" and have an Optical genius like Steve Swayze refigure it to his standards of perfection for a little more than half the price of a new mirror figured by the afformentioned optician.

True the all-new mirror will be based on pyrex, but as far as final PTV and smoothness...is there an appreciable (subjective) or testable (objective) difference between the two finished surfaces?

Maybe that's an obvious "NO" but if it is, I don't know that as I'm still quite a novice and certainly have no experience with having mirrors refigured and resurfaced.

Okay here's my dilemma: Buy a Coulter 13.1" and have an Optical genius like Steve Swayze refigure it to his standards of perfection for a little more than half the price of a new mirror figured by the afformentioned optician.
True the all-new mirror will be based on pyrex, but as far as final PTV and smoothness...is there an appreciable (subjective) or testable (objective) difference between the two finished surfaces?
Maybe that's an obvious "NO" but if it is, I don't know that as I'm still quite a novice and certainly have no experience with having mirrors refigured and resurfaced.

In a thread just below, Darren (thanking Michael) said:
"BTW, thanks for the Mars previewer link. I'm checking what's visible right now"

What Mars previewer link?

Thanks,
Tom

Hey kids. I am having a few people over Friday all of whom know I have a telescope and want to look at Mars....and some other things while they are at it.

Now, my 6" Intes MK67 Mak Newt gives some crisp views especially under dark skies, but from my urban location, it's hardly a light bucket, so showing M81/M82 is too suble for the uninitiate I think. Though it does shine my shoes, it's mostly for intellectual reasons, not visual...not from the city anyway. So I want to focus on a few other purely visual and not so subtle objects

So....Let me show you the list I have in my head at the moment....


1. Mars.
2. M13
3. M92
4. Ring
5. Alberio - for sure
6. Dumbell - too shapeless maybe?

I guess open clusters or dramatic red/blue doubles would be nice and easy to see and/or appreciate for my newbie guests.

Nothing beats the one two punch available in a few months of the giants...I just LOVE newbie reactions to that! But other than those, what is my best shot(s) at knocking their socks off on Friday night?

Thanks for any tips.

Tom.

The thread below starts by my asking for some good newbie crowd pleasers for the first real star party for friends I hosted last night. It concludes by saying it was a great success overall (didn't squeeze in any open clusters, which won't happen again, but did spend a good deal of time on the ring before mars stole the show), and my PS says, "never underestimate the unplanned, such as a spontaneous sattelite spotting game that unfolded as my friends waited for me to find the next object."

But what I didn't realize was that it was I who had the biggest surprise...unbeknownst to me....let me explain.

Soon after twilight. I pointed out how to find the north star (always a good place to start), using the big dipper pointer stars. Oh, so easy everyone sees the bright north star? yes, who wouldn't it's so bright and easy even though it's light out. GREAT..I thought...well, privately I thought, "huh? why the f*?# is it THAT bright? Plane? no, not moving. I guess I don't normally spend much time looking north when backyard observing...still it's hard to gague magnitude while it's still light out, but that's odd." someone else came over in about 45 minutes and I pointed it out to them too and I just remember thinking in passing, that it's a lot dimmer now that its dark.

But this morning there was a posting to my local club list...actually it was a week old, but i only saw it by chance this morning called "bright light in the sky". maybe i only bothered to read it because i had that little nagging suspicion i might have seen something out of the ordinary, but didn't know it. the answer was, "iridium 6". huh?

I looked it up, and for some reason (I've only been in this 18 months or so), I had NO IDEA what an irridim flare was (i thought it was like a chance meteorite type sighting, not predictible flare of discarded satelite reflective materials)...research after observing is probably the most rewarding aspect of this hobby! looked it up at heavens-above.com and guess what...EXACTLY the right time, EXACTLY the right location and lasting less than a minute. What luck! it was 6* away from true North, so in the twilight, that WAS the north star since it blew polaris away out of sight because it shone at -7 magnitude. All I did was thought, "plane? no, not moving. they're waiting...so point out "polaris" and move on...and forgot about it"

what fun that I had the biggest surprise in store...i thought I was just going to introduce others to new stuff, not suspecting I would be totally baffled and learn something totally new ... no prior knowledge of these AT ALL. It happens again with irridim 4 tonight at the same spot (for me). I'm all over it!

TomL

Hi All. I have finally decided to go for it and build a scope that will meet my personal criteria.

One of which is ultra fast setup without the need to recollimate every time. (thank you string scope!)

Another of which is a one-person-managable weight (preferably light, but I don't travel that often and can handle a bit of weight if it means getting everything else I want...I just mean I don't need a 20 pound ultramodern ultralightweight for it's own sake. I consider a 50 pound scope totally managable but of course light is good). I'm especially keen on getting down to a very compact 'package', that, if I need to fly with it, I could, say at worst, put the primary in a carry-on messenger bag, and check the rest as some kind of self-contained and sturdy BOX (nested and collapsed), at best bring the whole thing with primary in tact onto carry-on, but really that is probably pressing it though others have gone to great lengths to do just that:
http://members.aol.com/radcash/travelscope.htm


(i also want ladderless viewing with high quality optics and while I was considering 15 inches to be my maximum to meet the goals for this scope, I came into what promises to be an outstanding refigured 13.1 if all goes right, so for now it's going to be a 13.1, and the longer the better but f/5 may be the limit for flat footed -ish observing as I am 5'11", taller in heels, but so awkward to observe in drag!

I am sold on doing a string scope, but now must decide whether to do one of those boxless rockers whatever you call them (see pic) or a nesting UTA-collapsed-into-RockerBox, coupled with ground board, to lock up into a convenient travel box (minus trusses). An excellent example built by an 'internet friend' and sometime contributor to this forum is seen here:
http://home.europa.com/~telscope/tanaka.htm


What I need help with guys is this: having decided a lot already (13.1, string, goal is collapsability and a managable weight), what kind of rocker should I execute and why? pros? cons of each. I'm a so so wood worker, and not at all a metalworker if that makes any difference to your suggestion. I just don't know the relative advantages or disadvantages of this radical rocker (see pic) versus the other links I've included and that should settle my overall design approach for now.

Thanks.
TomL

I have heard that faster than f6, a newt starts to get finicky about needing collimation each time you go out, or being harder and harder to get it dead on. with bigger dobs though, you don't always have the luxury of a long FL, so for me at 5'11" (plus 1' for standing on my EP case) and a 13.1" mirror that's about 4" off the ground at zenith, I figure that f5.25 is my theoretical limit, but sure maybe f5.5 if I don't mind waiting for the odd thing at absolute zenith to 'move'. In that case, maybe a different step stool, or maybe a little more waiting could possibly maybe talk me into an f6, but that would give up some ease of use (tip toes + storage + bulk etc), which I really want to avoid if possible.

Still, finicky collimation impacts usability too, so what I want to know is:

what difference to the 'finicky' factor does f5.25, f5.5, and f6 make. I know we're not talking ultra fast or slow here, but a fine grained 'dialing' in on the usability/need for fine collimation versus quick and dirty being 'good enough' but as I get ready to refigure my mirror, I want to know what I should shoot for in trading off quick n dirty is good enough (that's good) with super tall scopes (not so good).

Thanks!
TomL